1-ethyl-3-methylimidazolium chloride ionic liquid enhance planar triple-cation perovskite solar cell efficiency

Although perovskite solar cells have made remarkable progress, the record device efficiency still lags far behind the theoretical limit efficiency. In this work, the ionic liquid, 1-ethyl-3-methylimidazolium chloride, is introduced into the triple-cation perovskite light absorption layer. The perovskite film with optimal amount of 1-ethyl-3-methylimidazolium chloride increases crystallinity, decreases pinholes and reduces defects density. As a result, the nonradiative recombination loss is efficiently restrained, accelerating the carrier extraction. The device modified with 1-ethyl-3-methylimidazolium chloride acquires a power conversion efficiency of 21.54%, which is considerably higher than that of the control device (18.12%). This work demonstrates that 1-ethyl-3-methylimidazolium chloride is a promising ionic liquid additive for high-performance perovskite solar cells.